Characterisation of Italian commercial apricot juices by high-performance liquid chromatography analysis and multivariate analysis

The modern fruit juice industry needs their products to be characterized by high-quality attributes to meet consumers’ expectation. In this view, the composition of 26 Italian commercial apricot juices obtained from organic, integrated and conventional agriculture was analysed for carbohydrates, organic acids, amino acids, phenolic compounds and furanic compounds by high-performance liquid chromatography (HPLC). The content of 5-hydroxymethylfurfural in apricot juices (range 0.1–18 mg/l) was within the regulatory limit of 20 mg/l. The lack of furanic compounds in apricot fresh fruits confirmed their importance as quality markers of heating condition during processing and storage of fruit juices. Univariate analysis disclosed some significant differences among the composition of the apricot juices in terms of glucose, fructose, malic acid, glycine, chlorogenic acid, rutin, and a^∗-parameter (redness). Principal component analysis on chemical composition of apricot juices resulted in two principal components (PCs) that accounted for 66% of the total variance. Organic apricot juices showed some separation from the other juices, whereas a lack of distinction between integrated and conventional juices appeared.     

Nachweis von Clostridium botulinum Typ A, B, E und F mittels real-time-PCR

Clostridium botulinum is a Gram-positive, anaerobic, spore-performing bacterium with the ability to produce under certain conditions a protein with a characteristical neurotoxicity. Intoxications with C. botulinum toxin belong to the rare occuring food-poisonings; the mortality, however, is very high. C. botulinum produce seven different toxin types (type A to G), human intoxications are currently described to caused by toxin type A, B, E and F. C. botulinum is a strictly anaerobic growing bacterium, so the risk for the consumer’s health is mainly due to non-commercially produced food cans. A special form of botulism is the „infant botulism“. In contrast to the botulism of adults, where the disease is caused through toxin-containing food, spores of C. botulinum can sporulate and produce toxin in the intestines of an infant. The source of infant botulism can be honey, because it contains as a natural product C. botulinum spores. Because of the difficult and time-consuming cultural detection of C. botulinum, PCR methods to screen for the toxin genes A, B, E and F, which are relevant in the human medicine, have been used increasingly during the last years. In this presentation two real-time-PCR assays for C. botulinum, which can be applied in the routine laboratory, will be shown.

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Zusammenfassung: Clostridium botulinum z?hlt zu den anaeroben sporenbildenden Bakterien, die unter bestimmten Bedingungen in der Lage sind, sich in Lebensmitteln zu vermehren und ein Protein mit charakteristischer Neurotoxizit?t zu bilden. Intoxikationen mit Clostridium botulinum-Toxin geh?ren zu den seltenen lebensmittelassoziierten Intoxikationen; die Mortalit?t bei einer Erkrankung ist allerdings sehr hoch. C. botulinum produziert sieben unterschiedliche Toxintypen (Typ A-G), wobei für menschliche Erkrankungsf?lle bisher die Toxintypen A, B, E und F beschrieben sind. Da es sich bei den genannten Keimen um strikt anaerob wachsende Bakterien handelt, stellen vor allem nicht kommerziell hergestellte Konserven, wie z. B. Kesselkonserven, ein Risiko für den Verbraucher dar. Als besondere Form des Botulismus wird der so genannte „S?uglingsbotulismus“ beschrieben. Im Gegensatz zur der Erkrankung, die bei Erwachsenen auftritt und die durch die Aufnahme des bereits toxinhaltigen Lebensmittels verursacht wird, k?nnen Sporen von C. botulinum im Darm von S?uglingen auskeimen und dort Toxine bilden. Ursache für den S?uglingsbotulismus ist h?ufig Honig, der als Naturprodukt C. botulinum-Sporen enthalten kann. Da der kulturelle Nachweis von C. botulinum aufwendig und eine endgültige Differenzierung schwierig ist, wird im Bereich der Routinediagnostik seit einigen Jahren verst?rkt mit PCR-Nachweisverfahren gearbeitet, die ein schnelles Screening auf das Vorhandensein der vier in der Humanmedizin relevanten Toxingene A, B, E und F erm?glichen. In dieser Arbeit werden zwei real-time-PCR-Systeme vorgestellt, die im Bereich der Routinediagnostik einsetzbar sind.

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Eingegangen: 19. Januar 2007     

Determination of melamine in milk and dairy products by high performance liquid chromatography

A simple, precise, accurate, and validated reverse-phase HPLC method was developed for the determination of melamine in milk (pasteurized and UHT milk) and dairy products (powdered infant formula, fruit yogurt, soft cheese, and milk powder). Following extraction with acetonitrile:water (50:50, vol/vol), samples were purified by filter (0.45 μm), separated on a Nucleosil C8 column (4.6 mm × 250 mm, 3 μm) with acetonitrile:10 mmol/L sodium L-octane sulfonate (pH 3.1; 15:85, vol/vol) as mobile phase at a flow rate of 1 mL/min, and determined by a photodiode array detector. A linear calibration curve was obtained in the concentration range from 0.05 to 5 mg/kg. Milk and dairy products were fortified with melamine at 4 levels producing average recovery yields of 95 to 109%. The limits of detection and quantification of melamine were 35 to 110 and 105 to 340 μg/kg, respectively. The method was then used to analyze 300 samples of milk and dairy products purchased from major retailers in Turkey. Melamine was not found in infant formulas and pasteurized UHT milk, whereas 2% of cheese, 8% of milk powder, and 44% of yogurt samples contained melamine at the 121, 694±146, and 294±98 μg/kg levels, respectively. These findings were below the limits set by the Codex Alimentarius Commission and European Union legislation. This is the first study to confirm the existence of melamine in milk and dairy products in Turkey. Consumption of foods containing these low levels of melamine does not constitute a health risk for consumers.     

Risk factors associated with lameness and hoof lesions in pasture-based dairy cattle systems in southeast Brazil

Cattle lameness is an important welfare concern that also has an economic impact on the dairy industry. It can be a significant problem among pasture-based herds. Our objectives were to identify cow- and herd-level factors related to lameness and hoof lesions in dairy cows grazing year-round in Minas Gerais, Brazil. We performed a cross-sectional study in 48 pasture-based dairy herds, visiting each farm in a single visit. We evaluated 2,262 cows for mobility score (0–3) and 392 cows for hoof lesions. We used a questionnaire and checklist to capture herd management data. All information obtained was used to build multivariable models. The factors associated with lameness were low body condition score, longer time spent in the corral, being kept in paddocks during the drought period, and poor hygiene. For hoof lesions, track features were the most significant factor in determining the likelihood of heel horn erosion, white line fissure, and sole hemorrhage—by more than 3 times. Different factors related to unhygienic conditions such as leg cleanliness, frequency of cleaning, and longer time spent in the corral were associated with infectious hoof lesions. Poor human–animal relationship was related to sole hemorrhage, but patient handling of cows on the track was a protective factor against interdigital hyperplasia. The results of this study suggest that improving hygiene conditions, track features, and cow handling can improve dairy cattle mobility scores in pasture-based farms under tropical conditions. These findings also represent a first step toward planning actions aimed at decreasing lameness and hoof lesions in the studied region.     

Zur Chemie der 3-Aroylimino-3H-1,2-dithiole

Reactions of 3-Aroylimino-3H-1,2-dithioles The thiolates 3 and 10 prepared from 3-aroylimino-4-aroylthio-5-cyano-3H-1,2-dithioles 1 with bases, react with alkylhalides and acylhalides to the corresponding 4-S-substituted compounds 6, 11 and 7 , respectively. Treatment of the thiolates with 1-chloropropanone gives the bicyclic compound 12 by intramolecular cyclization involving the 5-cyano-group. 3,6-Bis-(acylimino)-3H,6H-[4,3-c] [1,2]-dithioles 2 or 8 are prepared from the S-acylated dithioles 1 or 7 and sulphur in pyridine/benzene. 1,2,4-Triazines 13 are formed by the reaction of dithiol es 1 orthiolates 3 with phenylhydrazine. The thiolates give upon protonation the mesoionic dithioliumthiolates 4 . Coordination compounds are obtained from the reaction of the thiolates with cations of 3d-elements. On the basis of the chemical behaviour of the new 3-acylimino-1,2-dithioles and the results of spectroscopic measurements a strong bonding interaction between the N-acyl-carbonylgroup and the dithiole ring system in these compounds is supposed.     

Zur Beschreibung der Wechselwirkung zwischen p-substituierten Benzaldehyden und NMR-Verschiebungsreagenzien

Investigations to the Interaction between p-Substituted Benzaldehydes and N.M.R.-Shift Reagences The influence of n.m.r. shift reagents (Eu(fod)₃ and Pr(fod)₃) on the chemical shifts of p-dimethylaminobenzaldehyde has been investigated at ¹³C and ¹H-n.m.r. spectroscopy. The induced shifts of the protons are quantitatively explained on the basis of pseudocontact interaction. In ¹³C-n.m.r. spectra significant contact interactions have also been noted. The ¹³C induced shifts have been separated into pseudocontact and contact contributions by two different methods. Calculations of relative equilibrium constants in mixtures have been carried out for p-dimethylaminobenzaldehyde, p-nitrobenzaldehyde, anisaldehyde and benzaldehyde. The relative equilibrium constants show a good correlation with the Hammett substituent constants.     

Sterol glycosides and cerebrosides accumulate in Pichia pastoris, Rhynchosporium secalis and other fungi under normal conditions or under heat shock and ethanol stress

The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans, Pichia pastoris and Pichia anomala, as well as in the six fungal species Sordaria macrospora, Pyrenophora teres, Ustilago maydis, Acremonium chrysogenum, Penicillium olsonii and Rhynchosporium secalis. Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis, S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are beta-glucosyl ceramides consisting of a saturated alpha-hydroxy or non-hydroxy fatty acid and a Delta4,8-diunsaturated, C9-methyl-branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol-beta-D-glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae, new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the ubiquitous and frequent occurrence of cerebrosides and sterol glycosides, both of which are rarely detected in S. cerevisiae. We suggest P. pastoris and two plant pathogenic fungi to be selected for this approach.     

脂肪酶改良猪油制备功能性脂的研究

我国有丰富廉价的动植物油资源，但这一资源并末得到有效的利用，为了充分利用这些资源，开展了脂肪酶催化猪油与辛酸酸解制备功能性脂的研究工作。脂肪酶筛选实验表明，在所选用的五种脂肪酶中，来自T.languginosa的同定化脂肪酶Liopzyme TL IM的催化效果最好。以Lipozyme TL IM为催化剂，进一步研究了酶量、有机溶剂、底物比率、反心时间和反应温度对猪油中辛酸插入率的影响。反应产物通过高效液相色谱法（HPLC）进行分析。研究结果表明，在正己烷介质中，脂肪酶量为15％（底物重量厅分比），底物比率为1：2（猪油：辛酸）反应时间24h，反应温度为55～60℃时，辛酸插入率最高。